Most conventional shock absorbing devices for a bicycle seat are of the 3-point type, i.e., the front point is fixed and does not provide a shock absorbing function and the rear two points utilize spring compression or expansion for providing a shock absorbing function. However, these conventional shock devices for a bicycle seat have two disadvantages:
1. Their shock function depends on an up and down swinging displacement on the rear side of the seat while the front side of the seat remains stationary. Thus, the shock absorbing function is insufficient.
2. Because the shock spring is fixed, if the rider is too heavy it will be compressed and expanded to its limits so the shock absorbing effect is not significant. On the contrary, if the rider is too light, then the spring will be too stiff.
There are two major factors which cause shock to a bicycle during its operation, including a cavity in or a projection on the road. When the wheel runs over a cavity, the rider and bicycle will sink down promptly to cause an up and down shock. When the wheel runs over a projection, the rider and bicycle will experience a longitudinal shock impact. Thus, the shocks caused during operation include vertical and longitudinal shocks due to a series of cavities in and projections on the road.
In view of the foregoing, the invention provides a shock strut for a bicycle seat having a most convenient and effective design, and with the following advantages:
1. It has a shock absorbing function through vertical and longitudinal displacements for absorbing vertical and longitudinal impacts to the bicycle.
2. It can adapt to the need of the rider by properly adjusting the angle of inclination of the seat and the direction of the shock absorbing function.
3. It can adapt to the weight of the rider by appropriately adjusting the compression strength of the shock absorbing spring.
These and other objects and advantages of the present invention will become apparent to those skilled in the art upon considering the following detailed description of the preferred embodiment, together with the accompanying drawings.